(a) Technical Field
The present invention relates to a system for culturing and recovering micro algae while fixing carbon dioxide.
(b) Background Art
Exhaust gases including carbon dioxide in many fields of industry are required to be treated for environmental consideration. Carbon dioxide can be treated chemically or biologically. One of the biological treatment methods is to use micro algae performing carbon dioxide assimilation. The carbon dioxide treatment using micro algae, however, is slow and requires a large space, which makes it difficult to commercialize the treatment method.
FIG. 1 is a diagram illustrating a conventional system for culturing micro algae using air-lift bioreactors. In the conventional system, micro algae are cultured in a culture medium contained in an air-lift photo-bioreactor 1 or air-lift photo-bioreactors 1 installed in series. Carbon dioxide is supplied into the culture medium using a diffuser 2 installed on the bottom of the air-lift photo-bioreactor 1.
FIG. 2 is a diagram illustrating a conventional system for culturing micro algae using a photo-bioreactor having therein a separation membrane. Micro algae are cultured in a culture medium contained in a photo-bioreactor 5 provided with a separation membrane 7 and an agitator 6 therein. The culture medium and micro algae are discharged from the photo-bioreactor 5, passed through a hollow fiber membrane 8 with carbon dioxide being introduced, and then introduced to the photo-bioreactor 5.
These conventional systems, however, have problems. For example, the carbon dioxide utilization efficiency is relatively low, precipitated micro algae may cause clogging of a diffuser, a durable separation membrane is relatively expensive, the overall process is quite complicated, and a large space is required for operation of the systems.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.